1. Field of the Invention
The present invention relates to a high density near field optical recording/reproducing device which can increase a recording density significantly by overcoming a limit of light diffraction.
2. Background of the Related Art
In general, the optical data storage technology has been developed significantly centered on CD and DVD technologies, particularly the realization of a semiconductor blue laser, which permits 3 to 4 times of a recording density increase, makes a large capacity optical recording technology available. However, to meet current demands both for information on image of a higher resolution and a small sized, light weight, but large capacity information storage, which is essential for personal information terminal, a leap of increase of information recording density is required. As a technical response to the demands, even though improvements in the recording density of magnetic information recording device, such as hard disk used as supplementary recording device for a computer, the magnetic information recording device has difficulty in increasing the recording density compared to an optical recording medium which uses a concentrated laser beam in nature.
Theoretically, the optical recording technology has a limit of recording density dependent on a wavelength of a laser beam used for recording/reproduction of a data. In the optical recording technology, a minimum length of one bit of data mark can be expressed as the following equation.   d  =      λ          (              2        ⁢        NA            )      
Where, xcex denotes a wavelength of the laser beam, which is approx. 650 nm in a case of a semiconductor red laser beam, and approx. 410 nm in a case of a semiconductor blue laser beam. xe2x80x98NAxe2x80x99 denotes a numerical aperture, which is approx. 0.5xcx9c0.7 for a general optical system lens. Therefore, a minimum pitch of data tracks which can be distinguished is in a range of a wavelength, which is a limit of size reduction permitted by an increased recording density, that is caused by diffraction of the laser beam. A technology spot lighted to overcome the limit is the near field optical recording technology. In the near field optical recording technology, a light transmissive probe is put near to a beam of light within a wavelength, and input/output of the light through the probe is made possible, for overcoming a spatial resolution limit from the wavelength. As a method for realizing the near field optical recording technology, there is the SIL(Solid Immersion Lens) method of the Terastor in the USA that comes closest to practical use up to now, in which an NA value is increased by using an SIL, which reduces a focus point size of a laser beam used for recording/reproduction, that improves the spatial resolution limit caused by diffraction of light. This method is favorable in view of putting into practical use in that a related art optical recording/reproducing method using a lens system can be utilized. However, even if the SIL is employed, the limitation of the NA value is still a limit in improving the recording density. Other than this method, even though there is the NSOM(Near-Field Scanning Optical Microscopy) in which an optical fiber probe tip is put near to a beam within a wavelength of a recording/reproducing light, the NSOM has not been used for an information recording device because of technical difficulties, such as difficulty in continuously maintaining a distance between the optical fiber probe tip and a disc within a range of the near field, a low data recording/reproducing rate, and the like.
Accordingly, the present invention is directed to a near field optical recording/reproducing device that substantially obviates one or more and disadvantages of the related art.
An object of the present invention is to provide a near field optical recording/reproducing device which can improve a recording density by using a near field optical recording technology.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, the near field optical recording/reproducing device includes a light source for emitting a bean of light, a converging lens for converging the light emitted from the light source, and a near filed light generating part formed of a material of which light transmittance is varied with light temperature sectors.
The near field optical recording/reproducing device further includes a mirror for reflecting the light emitted from the light source toward the converging lens, a package housing for protecting the converging lens and the near field light generating part, and a supporter for supporting the mirror and the package housing.
The near field optical recording/reproducing device further includes a piece of optical fiber, or lens between the light source and the mirror for providing the light from the light source to the mirror.
The near field light generating part is formed of any one selected from VO2, Sb, and AgOx.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.